An appraisal is a multistep evaluation of real personal property that may serve one or more functions.  Appraisals use evaluation research methodologies to collect data to formulate an opinion of value.  Appraisals may be performed on site or by phone.  Because every appraisal is unique to a client's needs, appraisers take this into consideration and factor this when examining works of art.  The scope of the work, aka the assignment, determines which avenue(s) the appraiser uses.